We have also summarized the major epigenetic alterations in GBM–such as MGMT promoter methylation (a predictive biomarker for chemoradiotherapy), widespread histone deacetylation and gene silencing contributing to therapy resistance, and the pivotal role of modifiers like EZH2 in maintaining a resistant stem-like state–and linked these to potential interventions. The gene discussed is MGMT; the disease is glioblastoma.